Anterior stromal puncture has been proposed as a treatment for recalcitrant cases of recurrent corneal erosion by McLean et al., Ophthalmol., Vol. 93, 784-788 (1986). However, the surgical instruments available have been designed for use in quite different procedures and are not well suited for use in stromal puncture. Attempts to use both cystotomes and straight needles, e.g., tuberculin needles for stromal puncture have shown them to be difficult to use safely and to involve the risk of corneal perforation and possibly excessive scarring.
The present invention provides a stromal puncture needle of unique design which can readily be used by any ophthalmic surgeon, and the use of which is substantially free from the risk of corneal perforation. By the use of this invention scarring is also minimized.
In general, the needle of the invention comprises a conventional needle hub which serves for mounting the needle on any suitable handle. Fixed to and extending from the hub is a generally straight portion of a needle shaft from 19 to 31 gauge, preferably about 25 gauge. The length of the straight portion is not critical and at its end distal from the hub the shaft is bent through an angle of 35 .degree.-155.degree. to provide a generally straight extension having at its distal end a cutting tip forming an included angle of 75.degree.-105.degree. with the extension and lying in the same plane as that defined by the straight portion and the extension of the shaft. The tip lies on the same side of the extension as the convex side of the bend in the shaft and has a length of 0.1 to 0.6 mm measured from the adjacent side of the extension.
The needle may also be said to comprise a hub and a generally Z-shaped shaft having a proximal leg, an intermediate leg and a distal leg lying generally in a single plane with the proximal leg secured to and extending from the hub. The distal leg and intermediate leg are connected by a bend forming an included angle from 135.degree. to 155.degree.; the length of the intermediate leg may vary from 10 to 30 mm. The distal leg, which extends toward the axis of the proximal leg terminates in a sharpened cutting point or edge. The length of the distal leg is 0.1 to 0.6 mm measured from the adjacent side of the intermediate leg to the end of the cutting point, and the distal leg is approximately perpendicular to the intermediate leg. That is, the included angle between the intermediate leg and the distal leg is 75.degree..degree.-105.degree..